A backlight unit includes a light source which generates a first light; a quantum dots member which is spaced apart from the light source by a first distance and converts the first light into a second light; a guide member which lengthwise extends in a first direction and fixes positions of the light source and the quantum dots member; and an optical member which reflects the second light. The guide member guides the first light from the light source to the quantum dots member and guides the second light from the quantum dots member to the optical member.